1. Field of the Invention
This invention relates to machines which are used to apply granular fertilizer into the ground for agricultural purposes. More specifically, the invention relates to an improved apparatus for drilling a hole into the ground and for applying fertilizer into the hole which is more precise and longer lasting than machines which have heretofore been used.
2. Description of the Prior Art
A common technique for fertilizing trees and other plants in the agricultural industry today is to drill a hole in the ground and then to add fertilizer into the hole. At least one machine, which is disclosed in U.S. Pat. No. 3,695,193 to Maier, has been developed for automatically performing this type of fertilizing procedure.
Drilling and fertilizing machines such as that disclosed in the Maier patent can save a great deal of labor and time, particularly in large agricultural operations. However, one problem that has previously existed in such machines is their inability to precisely control the amount of fertilizer that is being applied into each hole after it is drilled. This can result in a waste of fertilizer, or in not enough fertilizer being applied to any one hole.
Another problem which plagues machines such as that disclosed in the Maier patent is the tendency of certain parts in their fertilizing dispensing system to become rusted or otherwise corroded during prolonged periods of use. This results in the need for frequent lubrication, or for replacement of those parts periodically.
Another problem with such machines is that their augers are difficult to laterally stabilize during drilling. This can result in holes being drilled which are larger than necessary and can create forces and jerks which can be transmitted to the operator through the machine.
Finally, such machines often require repositioning of the machine relative to the hole after drilling in order to apply fertilizer into the hole. This can make it difficult or tiresome to accurately guide the fertilizer into each hole.
It is clear that there has existed a long and unfilled need in the prior art for a soil drilling and fertilizing tool which is resistant to rust and corrosion, which provides lateral guidance for the auger element during drilling, which does not require repositioning of the machine relative to the hole after drilling to apply fertilizer into the hole and which is able to accurately apply a pre-measured amount of fertilizer into the hole.